Effects of methylprednisolone and MK-801 on functional recovery after experimental chronic spinal cord injury (original) (raw)

Study design: An experimental study was conducted to evaluate the eects of methylprednisolone and MK-801 after the compressive injury of spinal cord in rats. Objectives: To investigate the eect of methylprednisolone and non-competitive NMDA antagonist MK-801 in long-term functional outcome after spinal cord injury (SCI). Methods: A randomized group A of Sprague-Dawley rats were treated with MK-801 (1.0 mg/kg, n=10; Group A) after a compression injury. A group of methylprednisolone (MP)-treated (30 mg/kg, n=10; Group B) and non-treated animals (n=9; Group C) were included for comparison. The functional motor outcome such as inclined plane (IP), toe spreading re¯ex (TSR), and modi®ed Tarlov scale (TS) were measured in each animal at regular time points up to 8 weeks post-treatment. Histologically the injury site was scored in four groups and immunohistochemically Wallerian Degeneration (WD), astrocytosis and expression of b-amyloid protein was identi®ed. Results: In examining the IP data, no signi®cant dierence was recognized between the group means (P-value40.5). For the TSR, there were no dierences in the group responses. For the TS, the dierences were not statistically signi®cant. Only group B showed signi®cance in cavitation scores compared to group A (P40.0094), WD was signi®cantly dierent than group C (P40.03), astrocytosis was signi®cantly higher than group A (P40.001) and modest presence of b-amyloid protein. Conclusion: Our data indicate that one time bolus administration of MK-801 lacks any signi®cant eect on axonal function in chronically injured rats. Daily bolus administration of MP at 30 mg/kg also did not ensure a better functional outcome. Immunohistochemically we have been able to show signi®cant dierences in WD, astrocytosis and small insigni®cant changes in b-amyloid protein.